• Journal of Internet Computing and Services
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• v.11 no.6
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• pp.31-39
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• 2010

The Generalized Hough Transform(GHT) is the most used algorithm for circle detection with high accuracy. However, it requires many computation time, because many different templates are applied in order to find circles of various size. In the case of circle detection and tracking in video, the classical approach applies GHT for each frame in video and thus needs much high processing time for all frames. This paper proposes the fast GHT algorithm in video, using two consecutive frames are similar. In the proposed algorithm, a change-driven method conducts GHT only when two consecutive frames have many changes, and trajectory-based method does GHT in candidate areas and with candidate radius using circles detected in a previous frame. The algorithm can reduce computation time by reducing the number of frames, the edge count, and the number of searching circles, as factors which affects the speed of GHT. Our experimental results show that the algorithm successfully detects circles with less processing time and no loss of accuracy in video acquisited by a fixed camera and a moving camera.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.6
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• pp.487-501
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• 2002

The concentrations of gaseous (NO$_{x}$, SO$_2$, and $O_3$) and particulate (Elemental Carbon, EC and Organic Carbon, OC) pollutants were measured to evaluate the air quality of Kosan. Samples were taken at Kosan during ACE-Asia (Asian Pacific Regional Aerosol Characterization Experiment) IOP (Intensive Observation Period) (2001. 3. 21~2001. 5. 5). The mean concentrations of $O_3$(46.3$\pm$10.4 ppb) is higher than those at urban area such as Seoul and Busan in Korea. On the other hand, the mean concentrations of other gaseous species, NO$_{x}$(4.73$\pm$3.42 ppb) and SO$_2$(0.62$\pm$0.63 ppb) are lower than those at great cities. So we concluded that there are a few primary sources emitting atmospheric pollutants. The concentration of EC is higher and the concentration of OC is similar with or higher than those at other background sites. The recent EC concentration is higher than those measured before at Kosan. We concluded that there are more primary sources than other background sites and the amount of primary source have increased recently in Jeju. Backward trajectory and co..elation analysis were used to study where the air masses originated and distinguish the source of pollutants. While NO$_{x}$ and $O_3$ were mainly emitted and formed from Jeju inland area, concentrations of SO$_2$, OC and EC were affected by Asian Dust from China. Using the mean relative standard deviation of ozone, cleanness coefficient was obtained. The cleanness coefficient value, is 1.6 times larger than the value in 1992. Recently, the air quality of Kosan has been contaminated because of the Asian Dust events since spring and the rapid industrialization development.pment.

• Journal of Oral Medicine and Pain
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• v.22 no.2
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• pp.295-307
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• 1997

This study was performed to investigate the reproductibility of eccentric mandibular movements according to preferred chewing side, range of mouth opening, type of lateral guidance and involvement of temporomandibular disorders. 50 patients with temporomandibular disorders and 65 dental students without any signs and symptoms were randomly selected for this study as the patients group and the control group, respectively. For recording and observation of eccentric mandibular movement trajectory, BioEGN$^\textregistered$ of Biopak$^\textregistered$ system (Bioresearch Inc., USA) was used. Each eccentric movement to anterior, right and left side was performed three times similar to the movement pattern for Pantronic Reproducibility Index. mandibular path was analyzed by three dimensional positional change and the three paths from one direction were compared with one another. From this, reproducibility index of one-directional lateral movement could be calculated, and total reproducibility index, named BioEGN reproducibility index(BERI), was also computed from three-directional eccentric movement likewise. BioEGN reproducibility Index could have four value of score by small or large scale, and by outgoing or incoming movement. The data were analyzed by SAS/stat program and the results obtained were as follows: 1. Right side chewing subjects showed more consistent pattern In reproducibility index in comparison between patients group and control group than left chewing subjects have done, and reproducibility was low in patients group. However, there was no difference between the two stoups in bilateral chewing subjects. 2. There were no difference in reproducibility index between preferred chewing side and contralateral side in unilateral chewing subjects whereas reproducibility index in left side on outgoing movement were higher than in right side in bilateral chewing subjects. 3. Difference in total reproducibility index(BERI) between canine guidance group and non-canine guidance group were not observed though difference in reproducibility index on lateral movement were observed in part. 4. There were no difference in reproducibility index between affected side and contralateral side in unilaterally affected patients, and between unilaterally affected patients and bilaterally affected patients in patients group. 5. Highly significant positive correlationship were shown among the four 쇼pes of total reproducibility index(BERI) in total subjects, and range of clinical mouth opening was negatively correlated with BEBI on outgoing movements and with index on outgoing movement to preferred side.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.259-268
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• 2004

For the last years, it has become hot issue such as disposal of the treated wastewater, which caused by increment of a population and industrial development at the coastal areas. The ocean outfall system discharges primary or secondary treated effluent into coastline or at the deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the see, surface forming plume or jet, together with entraining the surrounding salt water and becomes very dilute. This paper deals ocean outfall design which effects to decision-making about marine environment management and wastewater treatment. In order to make predictions of dilution of discharged water and the trajectory of a plume, CORMIX has been used considering several elements including a seasonal and tidal changes. These solutions are strung together to provide basic data and general drawings for effective management of outfall.

• Journal of the Korean earth science society
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• v.30 no.5
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• pp.529-549
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• 2009

In 2007, just after the recession of the Changma, anomalously long rainy period (from July 30 to August 15) occurred in Korea. To identify the cause of the sustained rainy period, we performed synoptic analysis and the associated air motions. The behavior of each air parcel trajectory associated with atmospheric motion was then investigated. As a result, three particular phenomena occurring at latitudes lower than $40^{\circ}N$ were discovered. First, a mass of relatively cold air, referred to as E, made a deep intrusion from $20^{\circ}N$ to $60^{\circ}N$. Second, this intrusion was accompanied by another mass of air called dE. It was colder and drier than E and originated from the mid-troposphere over the tropical ocean. Third, dE and E rotated clockwise three times over a period of 17 days over the Northwestern Pacific and blocked the westerly waves imbedded in the zonal flow from propagating. Two additional phenomena were observed at latitudes higher than $40^{\circ}N$. First, the cold core system, while approaching from the west with low geopotential values at its center, was stagnated over Shanxi China. It enhanced the northward intrusion of dE and E, and then diminished. The subsequent low system showed similar evolution as the first one. Second, a warm core anticyclone was formed over Lake Baikal, blocking the westerlies for 13 days and contributed to the persistent northward incursion of warm moist air. Moreover, a horizontally extended intrusion of upper level clouds from the tropics to $50^{\circ}N$, which may be interpreted as a tropical plume, was found around the end of the period (from August 12 to 15, 2007) with successive tropical nights over Korea.

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.383-392
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• 1996

An observation and evaluation of the reproducibility of the mandibular movements has been a integral part of a test for mandibular function and dysfunction. After Pantographic Reproducibility Index(PRI) was introduced in dentistry, many authors have used the index for investigation of mandibular movement function, especially in condylar compartment. Howerer, the difficult and time-consuming work of instrumentation for getting the PRI has been a major obstacle in using pantograph. This study was performed to try a new mandibular reproducibility index, so-called BioEGN reproducibility index(BERI), calculated from mandibular trajectory recorded with BioEGN. 26 dental students without any signs and symptoms of temporomandibular disorders and 22 patients with temporomandibular disorders took part in this study and classed to control group and patients group, respectively. Pantronic and BioEGN were used to record and calculate the indices, PRI and BERI. PRI had only one value, but BERI had two values of outgoing and incoming movement in each scale. With two scales of small and large, as a result, BERI had four values in this study. PRI corresponded to BERI in small scale on outgoing total movements. The data were calculated and analyzed with SAS/stat program and the conclusion of this study were as follows : 1. In every scales, in each movement, BERI on outgoing movement in control group was lower than that in patients group, respectively, but BERI on incoming movement was only different in one side movement, that was, left excursion. 2. The difference between BERI on outgoing movement and BERI on incoming movement was only shown in small scale on total movements, not in each movement, in control group. However, there was generally a positive correlationship between BERI on outgoing movement and BERI on incoming movement in each movement in both groups. 3. Simple statistics of PRI was similar to that of BERI on total movements in small scale, but there was a negative correlation between PRI and BERI on total movements in large sclae only in patients group.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.156-165
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• 2015

A survivability-analysis program has been developed to analyze the ground collision risk of atmospheric reentry objects, such the upper stages of a launch vehicle or satellites, which move at or near the orbital velocity. The aero-thermodynamic load during the free fall, the temperature variation due to thermal load, and the phase shift after reaching the melting point are integrated into the 3 degree-of-freedom trajectory simulation of the reentry objects to analyze the size and weight of its debris impacting the ground. The analysis results of the present method for simple-shaped objects are compared with the data predicted by similar codes developed by NASA and ESA. Also, the analysis for actual reentry orbital objects has been performed, of which results are compared with the measurement data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.839-847
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• 2011

This paper proposes a new guidance law for increasing the lethality of munitions. The well known PNG (Proportional Navigation Guidance) is inadequate for the munitions because of some weaknesses. Even if the munition does not have the impact point error, the acceleration command is non zero because the line-of-sight changes at all times in flight. Therefore, we use a difference between a target and an impact point. This proposed guidance law is similar to PNG in the form, but this guidance law concentrates a correction rate of flight path angle instead of the LOS (Line of Sight) rate. The correction of flight path angle is defined as the amount of impact point error. This impact point error can be calculated by neural networks rapidly. Finally, we show that the simulation results prove the suitability of this law.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.629-639
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• 2016

Batch process TRN(Terrain Relative Navigation) using an altimeter is a technique to correct position by correlating a series of periodically measured terrain height profile and terrain height candidate profile of the DEM(Digital Elevation Map). However, it is generally known that the performance of TRN is degraded when measured terrain height profile and terrain height candidate profiles of the DEM are similar at hill or repetitive terrain. In this paper, area based terrain slope roughness index[11] is applied and area based terrain curvature roughness index which can detect similarity of terrain in ROI(Region Of Interest) is proposed to overcome this problem. Applying terrain roughness indexes to terrain relative navigation system of lunar lander, it is shown that TRN using area based terrain roughness results in improved performance compared to conventional trajectory based method through simulation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.72-75
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• 2003

In this research, we focused on the effects of the orifice internal flow such as cavitation and hydraulic flip. The breakup characteristics such as the breakup length and trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance to provide a lot of conditions of the orifice internal flow. It is found that cavitation bubbles that occur inside the sharp-edged orifice make the liquid jet ejecting from the orifice turbulent. In the orifices (L/d = 5), the hydraulic flip phenomenon is shown when the injection pressure is high. In case cavitation occurs it breaks up more earlier than that in case of non-cavitation. In case hydraulic flip occurs, since the area of the liquid jet becomes small, the breakup length is also small as that in case of cavitation. But the liquid column trajectories have a similar tendency irrespective of cavitation.